Selective deposition of silicon nitride films for spacer applications

ABSTRACT

Methods for forming a spacer comprising depositing a film on the top, bottom and sidewalls of a feature and treating the film to change a property of the film on the top and bottom of the feature so that the film can be selectively etched from the top and bottom of the feature relative to the film on the sidewalls of the feature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/307,537, filed Mar. 13, 2016, the entire disclosure of which ishereby incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates generally to methods of depositing thinfilms. In particular, the disclosure relates to processes for theselective deposition of silicon nitride films by spatial ALD.

BACKGROUND

Silicon nitride thin films as a dielectric layer have been widely usedin semiconductor fabrication processes. For example, SiN films are usedin multi-patterning processes as spacer materials to achieve smallerdevice dimensions without employing the most expensive EUV lithographytechnology. Additionally, SiN can be used as a gate spacer material toisolate gate structure and contact areas to minimize potential leakagecurrent.

Traditional silicon nitride spacer fabrication processes includeconformal SiN film deposition on 3D structures (e.g., fins) followed bydirectional plasma dry etching to remove the top and bottom layer whilekeeping the sidewall film as a spacer. However, it has been found thatthe dry etch process could insidiously damage the sidewall surface andchange the film properties; eventually affective device performance andyield.

Therefore, there is a need in the art for processes of depositing aselective spacer films.

SUMMARY

One or more embodiments of the disclosure are directed to processingmethods. A substrate surface having at least one feature thereon isprovided. The at least one feature comprises a top, a bottom and asidewall. A film is formed on the at least one feature so that the filmis formed on the top, bottom and sidewall. The film is treated with aplasma to change a property of the film on the top and bottom of thefeature so that the top and bottom of the feature have higher wet etchrates than the film on the sidewall.

Additional embodiments of the disclosure are directed to processingmethods comprising positioning a substrate surface in a processingchamber. The substrate surface has at least one feature thereon. The atleast one feature has a top, bottom and sidewalls. The substrate surfaceis exposed to a deposition environment comprising at least onedeposition cycle. The deposition cycle comprises sequential exposure toa silicon precursor and a nitrogen containing reactant to form a siliconnitride film on the top, bottom and sidewalls of the at least onefeature. The silicon nitride film is exposed to a treatment environmentto modify the silicon nitride film deposited on the top and bottom ofthe at least one feature so that the film on the top and bottom have ahigher wet etch rate than the film on the sidewalls. The treatmentenvironment comprises a plasma having a high ion concentration.

Further embodiments of the disclosure are directed to processing methodscomprising placing a substrate having a substrate surface with a featureinto a processing chamber comprising a plurality of process regions.Each process region is separated from adjacent process regions by a gascurtain. The feature comprises a top, a bottom and a sidewall. At leasta portion of the substrate surface is exposed to a first processcondition in a first process region of the processing chamber. The firstprocess condition comprises a silicon precursor. The substrate surfaceis laterally moved through a gas curtain to a second process region ofthe processing chamber. The substrate surface is exposed to a secondprocess condition in the second process region of the processingchamber. The second process condition comprises a nitrogen precursor.The substrate surface is laterally moved through a gas curtain to athird process region of the processing chamber. The substrate surface isexposed to a third process condition in the third process region of theprocessing chamber. The third process condition comprises a nitrogenreactant to form a silicon nitride film on the top, bottom and sidewallsof the feature. Exposure to the first process condition, the secondprocess condition and the third condition is repeated to form a siliconnitride film with a predetermined thickness. The substrate surface ismoved to a fourth process region of the processing chamber. The fourthprocess region comprises a treatment environment comprising a high ionconcentration plasma that selectively decreases the wet etch rate of thesilicon nitride film on the top and bottom of the feature.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 shows a cross-sectional view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 2 shows a partial perspective view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 3 shows a schematic view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 4 shows a schematic view of a portion of a wedge shaped gasdistribution assembly for use in a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 5 shows a schematic view of a batch processing chamber inaccordance with one or more embodiment of the disclosure; and

FIGS. 6A through 6E show a processing method in accordance with one ormore embodiment of the disclosure; and

FIG. 7 shows a schematic view of a cross-section of a plasma assemblywith a slot in accordance with one or more embodiment of the disclosure.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the disclosure, it isto be understood that the disclosure is not limited to the details ofconstruction or process steps set forth in the following description.The disclosure is capable of other embodiments and of being practiced orbeing carried out in various ways.

A “substrate” as used herein, refers to any substrate or materialsurface formed on a substrate upon which film processing is performedduring a fabrication process. For example, a substrate surface on whichprocessing can be performed include materials such as silicon, siliconoxide, strained silicon, silicon on insulator (SOI), carbon dopedsilicon oxides, amorphous silicon, doped silicon, germanium, galliumarsenide, glass, sapphire, and any other materials such as metals, metalnitrides, metal alloys, and other conductive materials, depending on theapplication. Substrates include, without limitation, semiconductorwafers. Substrates may be exposed to a pretreatment process to polish,etch, reduce, oxidize, hydroxylate, anneal and/or bake the substratesurface. In addition to film processing directly on the surface of thesubstrate itself, in the present disclosure, any of the film processingsteps disclosed may also be performed on an under-layer formed on thesubstrate as disclosed in more detail below, and the term “substratesurface” is intended to include such under-layer as the contextindicates. Thus for example, where a film/layer or partial film/layerhas been deposited onto a substrate surface, the exposed surface of thenewly deposited film/layer becomes the substrate surface.

As used in this specification and the appended claims, the terms“precursor”, “reactant”, “reactive gas” and the like are usedinterchangeably to refer to any gaseous species that can react with thesubstrate surface.

Some embodiments of the disclosure are directed to processes that use areaction chamber with multiple gas inlet channels that can be used forintroduction of different chemicals or plasma gases. Spatially, thesechannels are separated by inert purging gases and/or vacuum pumpingholes to create a gas curtain that minimizes or eliminates mixing ofgases from different channels to avoid unwanted gas phase reactions.Wafers moving through these different spatially separated channels getsequential and multiple surface exposures to different chemical orplasma environment so that layer by layer film growth in spatial ALDmode or surface etching process occur. In some embodiments, theprocessing chamber has modular architectures on gas distributioncomponents and each modular component has independent parameter control(e.g., RF or gas flow) to provide flexibility to control, for example,gas flow and/or RF exposure.

Some embodiments of the disclosure use spatial architectures andcomprise a first chemistry dosing on a substrate surface followed by asecond chemical exposure to react with the dosed chemistry to form afilm, followed by a third additional post treatment process. In use,embodiments of the disclosure have an ALD layer that can be exposed toin-situ post treatment. In some embodiments, the treatment is done once.In some embodiments, the treatment may be employed every cycle. Theminimum amount of treatment might be in the range of every 1 to 100deposition cycles or more.

Some embodiments of the disclosure are directed to selective SiNdeposition methods that allow for different film properties based on thedeposition location on a 3D structure. For example, a film deposited onthe top and bottom of a structure can be treated to have different filmproperties than a film deposited on the sidewall of the structure. Someembodiments of the disclosure advantageously provide methods of forminga film in which wet etching can selectively remove portions of the film(e.g., the top and bottom) while leaving other portions of the film(e.g., the sidewall) as a spacer. Some embodiments of the disclosure areadvantageously performed in a single processing chamber.

While the various embodiments of the disclosure are described withrespect to the deposition of silicon nitride films, those skilled in theart will understand that the disclosure is not so limited. Other filmscan be deposited, treated and etched to leave a spacer.

In some embodiments, the silicon nitride selective deposition includestwo processes in a single processing chamber: SiN film deposition andplasma treatment. A batch processing chamber can be used to process aspatial atomic layer deposition (ALD) sequence: silicon precursorexposure; nitrogen precursor exposure (thermal or plasma); RF plasmatreatment with, for example, N₂, NH₃, H₂ or O₂ gases (which can be mixedwith inert gases such as Ar or He). The silicon and nitrogen precursorsforming a conformal SiN film and the plasma treatment modifying the filmon the top and bottom of the feature. In some embodiments, the RF plasmatreatment uses a hardware configured to have a directional treatmenteffect on the film. The plasma treatment process could form either N—Hor Si—O bonds on the film surface and penetrate into the film a depthbased on the treatment time and RF power. This has been found to producehigher wet etch rates on the top and bottom of the feature. Thedeposition layer thickness and plasma treatment level can be adjusted toincrease the wet etch rate selectivity. Selective deposition in someembodiments is performed at wafer temperatures in the range of about200° C. to about 550° C. One or more embodiments advantageously providefilms in which a directional dry etch method is optional, such asphysical bombardment, because the as deposited film shows different filmproperties at the top/bottom than the sidewalls of the features and aconformal dry etching can selectively remove the top/bottom of the film.

Referring to FIGS. 6A through 6E, one or more embodiments of thedisclosure are directed to processing methods to deposit a spacer filmon a substrate surface 300 having a feature 310 thereon. The feature 310can be any three-dimensional structure that a film can be deposited on.The feature 310 shown in the Figures is a mandrel; however, thoseskilled in the art will understand that this is merely representative ofone possible structure. Suitable features 310 include, but are notlimited to, ridges, trenches and vias.

The feature 310 includes a top 320, a bottom 330 and a sidewall 340. Inthe embodiment shown, the feature 310 has two sidewalls 340 on eitherside of the feature 310. The feature 310 has a height defined by the top320 and bottom 330 and a width defined by the distance between thesidewalls 340.

The substrate surface 300 is provided with the at least one feature 310thereon. As used in this specification and the appended claims, the term“provided” used in this manner means that the substrate surface 300 isplaced or positioned in an environment for processing.

As shown in FIG. 6B, a film 350 is formed on the substrate surface 300so that the film forms on the at least one feature 310. The film 350forms on the top 320, bottom 330 and sidewalls 340 of the feature 310.In some embodiments, the film 350 forms conformally on the feature 310.As used herein, the term “conformal”, or “conformally”, refers to alayer that adheres to and uniformly covers exposed surfaces with athickness having a variation of less than 1% relative to the averagethickness of the film. For example, a 1,000 Å thick film would have lessthan a 10 Å variation in thickness. This thickness and variationincludes edges, corners, sides, and the bottom of recesses. For example,a conformal layer deposited by ALD in various embodiments of thedisclosure would provide coverage over the deposited region ofessentially uniform thickness on complex surfaces.

In some embodiments, the film 350 comprises SiN. The formation of theSiN can be performed by any suitable method including, but not limitedto, atomic layer deposition (ALD), plasma-enhanced atomic layerdeposition (PEALD), chemical vapor deposition (CVD) and plasma-enhancedchemical vapor deposition (PECVD). In some embodiments, the film 350 isSiN formed by and ALD process in which the substrate surface 300 issequentially exposed to a silicon precursor and a nitrogen reactant. Asused in this regard, a “silicon precursor” reacts with the surface ofthe substrate so that silicon molecules remain on the substrate surface.As used in this regard, a “nitrogen reactant” reacts with the siliconmolecules on the substrate surface.

In some embodiments, the SiN film is formed on the substrate surface 300with exposure to a nitrogen precursor between the exposure to thesilicon precursor and the nitrogen reactant. As used in this regard, a“nitrogen precursor” reacts with the substrate surface and minimallyreacts with the silicon species already on the substrate surface. Stateddifferently, the nitrogen precursor comprises a species that does notreact with silicon precursor molecules on the substrate surface. Theexposure to the nitrogen precursor can occur before, during or afterexposure to the silicon precursor as both the nitrogen precursor speciesand the silicon precursor species are reactive with the substratesurface and are minimally reactive with each other.

Suitable silicon precursors include, but are not limited to, silane,disilane, dichlorisilane (DCS), bis(diethylamino)silane (BDEAS),tetrakis(dimethylamino)silane (TDMAS) and/orbis(tertiary-butylamino)silane (BTBAS). In some embodiments, the siliconprecursor comprises dichlorosilane. In one or more embodiments, thesilicon precursor consists essentially of dichlorosilane meaning thatthere is less than 1% on an atomic basis of silicon species other thandichlorosilane.

Suitable nitrogen precursors include, but are not limited to, molecularnitrogen and ammonia. The process conditions employed during nitrogenprecursor exposure can affect the reactivity of the nitrogen specieswith the silicon species on the surface. In some embodiments, theprocess conditions are configured such that the nitrogen precursorreacts substantially only with the substrate surface. As used in thisregard, the term “substantially only” means that the nitrogen precursorreacts with less than about 10% of the surface silicon species.

The nitrogen reactant is a species that forms the silicon nitride filmon the substrate surface. In some embodiments, the nitrogen reactantprovides the nitrogen atoms for the formation of the nitride film (e.g.,SiN). In one or more embodiments, the nitrogen reactant does not includea nitrogen-containing species and forms the nitride film by facilitatinga reaction between surface species. Suitable nitrogen reactants include,but are not limited to, nitrogen plasma, ammonia plasma, a plasmacomprising a mixture of two or more of hydrogen, nitrogen, ammonia,helium, argon or oxygen. In some embodiments, the nitrogen reactantcomprises a plasma of argon and ammonia, or a plasma of argon andnitrogen, or a plasma of argon and oxygen, or a plasma of helium andammonia. In some embodiments, the nitrogen reactant comprises a plasmawithout nitrogen that reacts with the nitrogen species on the surface.In some embodiments, the nitrogen reactant comprises a plasma ofhydrogen and argon, or a plasma of hydrogen and nitrogen, or a plasma ofhydrogen and helium, or a plasma of hydrogen and ammonia, or a plasma ofhydrogen and oxygen.

As shown in FIG. 6C, after formation of the film 350 (e.g., siliconnitride), the film 350 is treated with a plasma 360 having a high ionconcentration. The plasma 360 can be a directional plasma. As used inthis specification and the appended claims, the term “directionalplasma” means that the energetic species present in the plasma (ions andradicals) move in a specified direction. For example, in FIG. 6C, theplasma 360 is illustrated moving downward so that the energetic speciesare able to contact the film 350 on the top surface 320 and bottomsurface 330 but have minimal contact with the film 350 on the sidewalls340.

A plasma with a high ion concentration has a concentration greater thanor equal to about 10¹⁰/cm³. In one or more embodiments, the plasma withthe high ion concentration has a concentration greater than or equal toabout 10⁹/cm³, 10¹¹/cm³, 10¹²/cm³, 10¹³/cm³ or 10¹⁴/cm³.

A directional plasma can be formed as a remote plasma in which theplasma species are excited remotely from the substrate surface and flowtoward the substrate surface. The substrate and substrate support maynot be part of the electrical path used to generate the plasma. Adirectional plasma may also be formed as a direct plasma in which thesubstrate or substrate support serve as an electrode in the plasmaformation. A direct plasma is generally a diffuse plasma and can be madedirectional by applying a bias to the substrate so that the ions areattracted to and move toward the substrate.

As shown in FIG. 6D, treating the film 350 with the plasma having a highion concentration modifies a property of the film 350 at the top 320 andbottom 330. In some embodiments, the property of the film 350 that ischanged to form the modified top film 352 and modified bottom film 353affects the wet etch rate in dilute HF (1%) so that the modified topfilm 352 and modified bottom film 353 can be etched from the feature 310without substantially affecting the sidewall film 354. In someembodiments, the treatment damages the film 350 on the top and bottom ofthe feature 310 so that the film can be selectively etched relative tothe sidewall.

In some embodiments, the wet etch rate of the modified top film 352 andmodified bottom film 353 is greater than or equal to about 15 Å/min. Insome embodiments, the wet etch rate of the modified top film 352 andmodified bottom film 353 is greater than or equal to about 20 Å/min or25 Å/min. In some embodiments, the wet etch rate of the modified topfilm 352 and modified bottom film 353 is greater than 2 times the wetetch rate of the sidewall film 354, or greater than 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15 times.

The plasma used in the treatment can be any suitable plasma (e.g.,direct or remote) which is capable of modifying the film properties. Insome embodiments, the treatment comprises one or more of hydrogen,argon, nitrogen, ammonia, oxygen or helium.

The amount of time used for treatment may affect the amount of damagecaused to the film on the top and bottom of the feature. The plasmaspecies and power may affect the depth of the damage caused to the film.A treatment process that causes deeper damage to the film can berepeated less often than a treatment process that causes shallowerdamage to the film. For example, a He/NH₃ plasma may cause deeper damagethan an Ar/NH₃ plasma so that the film deposited can be thicker beforetreating with the He/NH₃ plasma.

The formation and treatment of the film 350 can be repeated until a filmwith a predetermined total thickness has been formed. Each step in thefilm formation process can be sequentially repeated to form a film fortreatment. The film can then be treated and the process repeated. Insome embodiments, treating the film 350 with the plasma 360 occurs aftera film having a thickness in the range of about 1 Å to about 50 Å isdeposited. Stated differently, the film 350 is treated after about 1 Åto about 50 Å has been deposited.

In some embodiments of the method, the film 350 is etched. The modifiedtop film 352 and modified bottom film 353 are selectively etchedrelative to the sidewall film 354. As used in this regard, selectivelyetching means that the amount, rate, or degree of etching on the top andbottom is greater than the etching on the sidewall. In some embodiments,the film is etched with dilute HF to selectively remove the film fromthe top and bottom of the feature. FIG. 6E shows the result of an etchprocess. While the drawing shows square corners for the top and bottomof the feature 310 and the sidewall film 354, those skilled in the artwill understand that this is merely illustrative and that the edges andcorners are not perfectly straight or square.

Some embodiments of the disclosure are directed to processes ofdepositing a spacer material using a batch processing chamber, alsoreferred to as a spatial processing chamber. FIG. 1 shows across-section of a processing chamber 100 including a gas distributionassembly 120, also referred to as injectors or an injector assembly, anda susceptor assembly 140. The gas distribution assembly 120 is any typeof gas delivery device used in a processing chamber. The gasdistribution assembly 120 includes a front surface 121 which faces thesusceptor assembly 140. The front surface 121 can have any number orvariety of openings to deliver a flow of gases toward the susceptorassembly 140. The gas distribution assembly 120 also includes an outeredge 124 which in the embodiments shown, is substantially round.

The specific type of gas distribution assembly 120 used can varydepending on the particular process being used. Embodiments of thedisclosure can be used with any type of processing system where the gapbetween the susceptor and the gas distribution assembly is controlled.While various types of gas distribution assemblies can be employed(e.g., showerheads), embodiments of the disclosure may be particularlyuseful with spatial gas distribution assemblies which have a pluralityof substantially parallel gas channels. As used in this specificationand the appended claims, the term “substantially parallel” means thatthe elongate axis of the gas channels extend in the same generaldirection. There can be slight imperfections in the parallelism of thegas channels. In a binary reaction, the plurality of substantiallyparallel gas channels can include at least one first reactive gas Achannel, at least one second reactive gas B channel, at least one purgegas P channel and/or at least one vacuum V channel. The gases flowingfrom the first reactive gas A channel(s), the second reactive gas Bchannel(s) and the purge gas P channel(s) are directed toward the topsurface of the wafer. Some of the gas flow moves horizontally across thesurface of the wafer and out of the process region through the purge gasP channel(s). A substrate moving from one end of the gas distributionassembly to the other end will be exposed to each of the process gasesin turn, forming a layer on the substrate surface.

In some embodiments, the gas distribution assembly 120 is a rigidstationary body made of a single injector unit. In one or moreembodiments, the gas distribution assembly 120 is made up of a pluralityof individual sectors (e.g., injector units 122), as shown in FIG. 2.Either a single piece body or a multi-sector body can be used with thevarious embodiments of the disclosure described.

A susceptor assembly 140 is positioned beneath the gas distributionassembly 120. The susceptor assembly 140 includes a top surface 141 andat least one recess 142 in the top surface 141. The susceptor assembly140 also has a bottom surface 143 and an edge 144. The recess 142 can beany suitable shape and size depending on the shape and size of thesubstrates 60 being processed. In the embodiment shown in FIG. 1, therecess 142 has a flat bottom to support the bottom of the wafer;however, the bottom of the recess can vary. In some embodiments, therecess has step regions around the outer peripheral edge of the recesswhich are sized to support the outer peripheral edge of the wafer. Theamount of the outer peripheral edge of the wafer that is supported bythe steps can vary depending on, for example, the thickness of the waferand the presence of features already present on the back side of thewafer.

In some embodiments, as shown in FIG. 1, the recess 142 in the topsurface 141 of the susceptor assembly 140 is sized so that a substrate60 supported in the recess 142 has a top surface 61 substantiallycoplanar with the top surface 141 of the susceptor 140. As used in thisspecification and the appended claims, the term “substantially coplanar”means that the top surface of the wafer and the top surface of thesusceptor assembly are coplanar within ±0.2 mm. In some embodiments, thetop surfaces are coplanar within ±0.15 mm, ±0.10 mm or ±0.05 mm.

The susceptor assembly 140 of FIG. 1 includes a support post 160 whichis capable of lifting, lowering and rotating the susceptor assembly 140.The susceptor assembly may include a heater, or gas lines, or electricalcomponents within the center of the support post 160. The support post160 may be the primary means of increasing or decreasing the gap betweenthe susceptor assembly 140 and the gas distribution assembly 120, movingthe susceptor assembly 140 into proper position. The susceptor assembly140 may also include fine tuning actuators 162 which can makemicro-adjustments to susceptor assembly 140 to create a predeterminedgap 170 between the susceptor assembly 140 and the gas distributionassembly 120.

In some embodiments, the gap 170 distance is in the range of about 0.1mm to about 5.0 mm, or in the range of about 0.1 mm to about 3.0 mm, orin the range of about 0.1 mm to about 2.0 mm, or in the range of about0.2 mm to about 1.8 mm, or in the range of about 0.3 mm to about 1.7 mm,or in the range of about 0.4 mm to about 1.6 mm, or in the range ofabout 0.5 mm to about 1.5 mm, or in the range of about 0.6 mm to about1.4 mm, or in the range of about 0.7 mm to about 1.3 mm, or in the rangeof about 0.8 mm to about 1.2 mm, or in the range of about 0.9 mm toabout 1.1 mm, or about 1 mm.

The processing chamber 100 shown in the Figures is a carousel-typechamber in which the susceptor assembly 140 can hold a plurality ofsubstrates 60. As shown in FIG. 2, the gas distribution assembly 120 mayinclude a plurality of separate injector units 122, each injector unit122 being capable of depositing a film on the wafer, as the wafer ismoved beneath the injector unit. Two pie-shaped injector units 122 areshown positioned on approximately opposite sides of and above thesusceptor assembly 140. This number of injector units 122 is shown forillustrative purposes only. It will be understood that more or lessinjector units 122 can be included. In some embodiments, there are asufficient number of pie-shaped injector units 122 to form a shapeconforming to the shape of the susceptor assembly 140. In someembodiments, each of the individual pie-shaped injector units 122 may beindependently moved, removed and/or replaced without affecting any ofthe other injector units 122. For example, one segment may be raised topermit a robot to access the region between the susceptor assembly 140and gas distribution assembly 120 to load/unload substrates 60.

Processing chambers having multiple gas injectors can be used to processmultiple wafers simultaneously so that the wafers experience the sameprocess flow. For example, as shown in FIG. 3, the processing chamber100 has four gas injector assemblies and four substrates 60. At theoutset of processing, the substrates 60 can be positioned between theinjector assemblies 30. Rotating 17 the susceptor assembly 140 by 45°will result in each substrate 60 which is between gas distributionassemblies 120 to be moved to an gas distribution assembly 120 for filmdeposition, as illustrated by the dotted circle under the gasdistribution assemblies 120. An additional 45° rotation would move thesubstrates 60 away from the injector assemblies 30. The number ofsubstrates 60 and gas distribution assemblies 120 can be the same ordifferent. In some embodiments, there are the same numbers of wafersbeing processed as there are gas distribution assemblies. In one or moreembodiments, the number of wafers being processed are fraction of or aninteger multiple of the number of gas distribution assemblies. Forexample, if there are four gas distribution assemblies, there are 4xwafers being processed, where x is an integer value greater than orequal to one. In an exemplary embodiment, the gas distribution assembly120 includes eight process regions separated by gas curtains and thesusceptor assembly 140 can hold six wafers.

The processing chamber 100 shown in FIG. 3 is merely representative ofone possible configuration and should not be taken as limiting the scopeof the disclosure. Here, the processing chamber 100 includes a pluralityof gas distribution assemblies 120. In the embodiment shown, there arefour gas distribution assemblies (also called injector assemblies 30)evenly spaced about the processing chamber 100. The processing chamber100 shown is octagonal; however, those skilled in the art willunderstand that this is one possible shape and should not be taken aslimiting the scope of the disclosure. The gas distribution assemblies120 shown are trapezoidal, but can be a single circular component ormade up of a plurality of pie-shaped segments, like that shown in FIG.2.

The embodiment shown in FIG. 3 includes a load lock chamber 180, or anauxiliary chamber like a buffer station. This chamber 180 is connectedto a side of the processing chamber 100 to allow, for example thesubstrates (also referred to as substrates 60) to be loaded/unloadedfrom the chamber 100. A wafer robot may be positioned in the chamber 180to move the substrate onto the susceptor.

Rotation of the carousel (e.g., the susceptor assembly 140) can becontinuous or intermittent (discontinuous). In continuous processing,the wafers are constantly rotating so that they are exposed to each ofthe injectors in turn. In discontinuous processing, the wafers can bemoved to the injector region and stopped, and then to the region 84between the injectors and stopped. For example, the carousel can rotateso that the wafers move from an inter-injector region across theinjector (or stop adjacent the injector) and on to the nextinter-injector region where the carousel can pause again. Pausingbetween the injectors may provide time for additional processing stepsbetween each layer deposition (e.g., exposure to plasma).

FIG. 4 shows a sector or portion of a gas distribution assembly 220,which may be referred to as an injector unit 122. The injector units 122can be used individually or in combination with other injector units.For example, as shown in FIG. 5, four of the injector units 122 of FIG.4 are combined to form a single gas distribution assembly 220. (Thelines separating the four injector units are not shown for clarity.)While the injector unit 122 of FIG. 4 has both a first reactive gas port125 and a second gas port 135 in addition to purge gas ports 155 andvacuum ports 145, an injector unit 122 does not need all of thesecomponents.

Referring to both FIGS. 4 and 5, a gas distribution assembly 220 inaccordance with one or more embodiment may comprise a plurality ofsectors (or injector units 122) with each sector being identical ordifferent. The gas distribution assembly 220 is positioned within theprocessing chamber and comprises a plurality of elongate gas ports 125,135, 145 in a front surface 121 of the gas distribution assembly 220.The plurality of elongate gas ports 125, 135, 145, 155 extend from anarea adjacent the inner peripheral edge 123 toward an area adjacent theouter peripheral edge 124 of the gas distribution assembly 220. Theplurality of gas ports shown include a first reactive gas port 125, asecond gas port 135, a vacuum port 145 which surrounds each of the firstreactive gas ports and the second reactive gas ports and a purge gasport 155.

With reference to the embodiments shown in FIG. 4 or 5, when statingthat the ports extend from at least about an inner peripheral region toat least about an outer peripheral region, however, the ports can extendmore than just radially from inner to outer regions. The ports canextend tangentially as vacuum port 145 surrounds reactive gas port 125and reactive gas port 135. In the embodiment shown in FIGS. 4 and 5, thewedge shaped reactive gas ports 125, 135 are surrounded on all edges,including adjacent the inner peripheral region and outer peripheralregion, by a vacuum port 145.

Referring to FIG. 4, as a substrate moves along path 127, each portionof the substrate surface is exposed to the various reactive gases. Tofollow the path 127, the substrate will be exposed to, or “see”, a purgegas port 155, a vacuum port 145, a first reactive gas port 125, a vacuumport 145, a purge gas port 155, a vacuum port 145, a second gas port 135and a vacuum port 145. Thus, at the end of the path 127 shown in FIG. 4,the substrate has been exposed to the first reactive gas 125 and thesecond reactive gas 135 to form a layer. The injector unit 122 shownmakes a quarter circle but could be larger or smaller. The gasdistribution assembly 220 shown in FIG. 5 can be considered acombination of four of the injector units 122 of FIG. 4 connected inseries.

The injector unit 122 of FIG. 4 shows a gas curtain 150 that separatesthe reactive gases. The term “gas curtain” is used to describe anycombination of gas flows or vacuum that separate reactive gases frommixing. The gas curtain 150 shown in FIG. 4 comprises the portion of thevacuum port 145 next to the first reactive gas port 125, the purge gasport 155 in the middle and a portion of the vacuum port 145 next to thesecond gas port 135. This combination of gas flow and vacuum can be usedto prevent or minimize gas phase reactions of the first reactive gas andthe second reactive gas.

Referring to FIG. 5, the combination of gas flows and vacuum from thegas distribution assembly 220 form a separation into a plurality ofprocess regions 250. The process regions are roughly defined around theindividual gas ports 125, 135 with the gas curtain 150 between 250. Theembodiment shown in FIG. 5 makes up eight separate process regions 250with eight separate gas curtains 150 between. A processing chamber canhave at least two process region. In some embodiments, there are atleast three, four, five, six, seven, eight, nine, 10, 11 or 12 processregions.

During processing a substrate may be exposed to more than one processregion 250 at any given time. However, the portions that are exposed tothe different process regions will have a gas curtain separating thetwo. For example, if the leading edge of a substrate enters a processregion including the second gas port 135, a middle portion of thesubstrate will be under a gas curtain 150 and the trailing edge of thesubstrate will be in a process region including the first reactive gasport 125.

A factory interface 280, which can be, for example, a load lock chamber,is shown connected to the processing chamber 100. A substrate 60 isshown superimposed over the gas distribution assembly 220 to provide aframe of reference. The substrate 60 may often sit on a susceptorassembly to be held near the front surface 121 of the gas distributionplate 120. The substrate 60 is loaded via the factory interface 280 intothe processing chamber 100 onto a substrate support or susceptorassembly (see FIG. 3). The substrate 60 can be shown positioned within aprocess region because the substrate is located adjacent the firstreactive gas port 125 and between two gas curtains 150 a, 150 b.Rotating the substrate 60 along path 127 will move the substratecounter-clockwise around the processing chamber 100. Thus, the substrate60 will be exposed to the first process region 250 a through the eighthprocess region 250 h, including all process regions between.

Embodiments of the disclosure are directed to processing methodscomprising a processing chamber 100 with a plurality of process regions250 a-250 h with each process region separated from an adjacent regionby a gas curtain 150. For example, the processing chamber shown in FIG.5. The number of gas curtains and process regions within the processingchamber can be any suitable number depending on the arrangement of gasflows. The embodiment shown in FIG. 5 has eight gas curtains 150 andeight process regions 250 a-250 h.

A plurality of substrates 60 are positioned on a substrate support, forexample, the susceptor assembly 140 shown FIGS. 1 and 2. The pluralityof substrates 60 are rotated around the process regions for processing.Generally, the gas curtains 150 are engaged (gas flowing and vacuum on)throughout processing including periods when no reactive gas is flowinginto the chamber.

Accordingly, one or more embodiments of the disclosure are directed toprocessing methods utilizing a batch processing chamber like that shownin FIG. 5. A substrate 60 is placed into the processing chamber whichhas a plurality of sections 250, each section separated from adjacentsection by a gas curtain 150.

Some embodiments of the method comprise exposing a substrate surfacehaving a feature thereon to a deposition environment to deposit a film.As used in this regard, a “deposition environment” comprises one or moreprocess regions or process conditions that individually or sequentiallydeposit a film.

In an exemplary process, at least a portion of the substrate surface isexposed to a first process condition in a first section 250 a of theprocessing chamber. The first process condition of some embodimentscomprises a silicon precursor to form a silicon film. In one or moreembodiments, the first process condition comprises dichlorosilane.

The substrate surface is laterally moved through a gas curtain 150 to asecond section 250 b. The silicon layer is exposed to a second processcondition in the second section 250 b. The second process condition ofsome embodiments comprises a nitrogen precursor to form a nitrogen film.In one or more embodiments, the second process condition comprisesammonia.

The substrate surface is laterally moved from the second process regionto a third section 250 c. The third section 250 c of some embodimentscomprises a third process condition comprising a reactant to form a filmon the top, bottom and sidewalls of the feature. The fourth section 250d may comprise an inert environment. In some embodiments, the thirdsection 250 c comprises an inert environment so that there issubstantially no surface reaction and the fourth section 250 d comprisesthe third process condition. In one or more embodiments, the thirdprocess condition comprises a N₂/Ar plasma.

The exposure to the first process condition, the second processcondition and the third process condition can be repeated to form a filmwith a predetermined thickness. For example, referring to FIG. 5, thefirst section 250 a and fifth section 250 e may comprise the firstprocess condition; the second section 250 b and sixth section 250 f maycomprise the second process condition; the third section 250 c andseventh section 250 g may comprise an inert environment; and the fourthsection 250 d and eighth section 250 h may comprise the third processcondition. In this arrangement, each rotation of the substrate forms twolayers. Those skilled in the art will understand that the use ofordinals such as “first” and “second” to describe process regions do notimply a specific location within the processing chamber, or order ofexposure within the processing chamber.

Once a layer of a predetermined thickness has been formed, the firstprocess condition, second process condition and third process conditionmay be changed to inert environments. The inert environment in the thirdsection 250 c, for example, can be changed to a treatment environmentcomprising a high ion concentration plasma that selectively decreasesthe wet etch rate of the silicon nitride film on the top and bottom ofthe feature. For example, the high ion concentration plasma may compriseHe/NH₃. After exposure to the treatment environment, the individualsections of the processing chamber can be changed back to the previoussettings or the process can be stopped.

Referring to FIG. 7, some embodiments use a plasma assembly 380 with aslot 382. The plasma forms in the plasma cavity 384 and flows throughthe slot 382 toward the substrate surface 300. The view shown in FIG. 7is a cross-sectional view in which the slot 382 extends out of the page.The slot 382 through which the plasma formed in plasma cavity 384 flowshas edges 386. In some embodiments, the plasma has a high ion energy andconcentration adjacent the edges 386 of the slot 382.

According to one or more embodiments, the substrate is subjected toprocessing prior to and/or after forming the layer. This processing canbe performed in the same chamber or in one or more separate processingchambers. In some embodiments, the substrate is moved from the firstchamber to a separate, second chamber for further processing. Thesubstrate can be moved directly from the first chamber to the separateprocessing chamber, or it can be moved from the first chamber to one ormore transfer chambers, and then moved to the separate processingchamber. Accordingly, the processing apparatus may comprise multiplechambers in communication with a transfer station. An apparatus of thissort may be referred to as a “cluster tool” or “clustered system,” andthe like.

Generally, a cluster tool is a modular system comprising multiplechambers which perform various functions including substratecenter-finding and orientation, annealing, annealing, deposition and/oretching. According to one or more embodiments, a cluster tool includesat least a first chamber and a central transfer chamber. The centraltransfer chamber may house a robot that can shuttle substrates betweenand among processing chambers and load lock chambers. The transferchamber is typically maintained at a vacuum condition and provides anintermediate stage for shuttling substrates from one chamber to anotherand/or to a load lock chamber positioned at a front end of the clustertool. Two well-known cluster tools which may be adapted for the presentdisclosure are the Centura® and the Endura®, both available from AppliedMaterials, Inc., of Santa Clara, Calif. However, the exact arrangementand combination of chambers may be altered for purposes of performingspecific steps of a process as described herein. Other processingchambers which may be used include, but are not limited to, cyclicallayer deposition (CLD), atomic layer deposition (ALD), chemical vapordeposition (CVD), physical vapor deposition (PVD), etch, pre-clean,chemical clean, thermal treatment such as RTP, plasma nitridation,anneal, orientation, hydroxylation and other substrate processes. Bycarrying out processes in a chamber on a cluster tool, surfacecontamination of the substrate with atmospheric impurities can beavoided without oxidation prior to depositing a subsequent film.

According to one or more embodiments, the substrate is continuouslyunder vacuum or “load lock” conditions, and is not exposed to ambientair when being moved from one chamber to the next. The transfer chambersare thus under vacuum and are “pumped down” under vacuum pressure. Inertgases may be present in the processing chambers or the transferchambers. In some embodiments, an inert gas is used as a purge gas toremove some or all of the reactants. According to one or moreembodiments, a purge gas is injected at the exit of the depositionchamber to prevent reactants from moving from the deposition chamber tothe transfer chamber and/or additional processing chamber. Thus, theflow of inert gas forms a curtain at the exit of the chamber.

The substrate can be processed in single substrate deposition chambers,where a single substrate is loaded, processed and unloaded beforeanother substrate is processed. The substrate can also be processed in acontinuous manner, similar to a conveyer system, in which multiplesubstrate are individually loaded into a first part of the chamber, movethrough the chamber and are unloaded from a second part of the chamber.The shape of the chamber and associated conveyer system can form astraight path or curved path. Additionally, the processing chamber maybe a carousel in which multiple substrates are moved about a centralaxis and are exposed to deposition, etch, annealing, cleaning, etc.processes throughout the carousel path.

During processing, the substrate can be heated or cooled. Such heatingor cooling can be accomplished by any suitable means including, but notlimited to, changing the temperature of the substrate support andflowing heated or cooled gases to the substrate surface. In someembodiments, the substrate support includes a heater/cooler which can becontrolled to change the substrate temperature conductively. In one ormore embodiments, the gases (either reactive gases or inert gases) beingemployed are heated or cooled to locally change the substratetemperature. In some embodiments, a heater/cooler is positioned withinthe chamber adjacent the substrate surface to convectively change thesubstrate temperature.

The substrate can also be stationary or rotated during processing. Arotating substrate can be rotated continuously or in discreet steps. Forexample, a substrate may be rotated throughout the entire process, orthe substrate can be rotated by a small amount between exposures todifferent reactive or purge gases. Rotating the substrate duringprocessing (either continuously or in steps) may help produce a moreuniform deposition or etch by minimizing the effect of, for example,local variability in gas flow geometries.

In atomic layer deposition type chambers, the substrate can be exposedto the first and second precursors either spatially or temporallyseparated processes. Temporal ALD is a traditional process in which thefirst precursor flows into the chamber to react with the surface. Thefirst precursor is purged from the chamber before flowing the secondprecursor. In spatial ALD, both the first and second precursors aresimultaneously flowed to the chamber but are separated spatially so thatthere is a region between the flows that prevents mixing of theprecursors. In spatial ALD, the substrate is moved relative to the gasdistribution plate, or vice-versa.

In embodiments, where one or more of the parts of the methods takesplace in one chamber, the process may be a spatial ALD process. Althoughone or more of the chemistries described above may not be compatible(i.e., result in reaction other than on the substrate surface and/ordeposit on the chamber), spatial separation ensures that the reagentsare not exposed to each in the gas phase. For example, temporal ALDinvolves the purging the deposition chamber. However, in practice it issometimes not possible to purge the excess reagent out of the chamberbefore flowing in additional regent. Therefore, any leftover reagent inthe chamber may react. With spatial separation, excess reagent does notneed to be purged, and cross-contamination is limited. Furthermore, alot of time can be used to purge a chamber, and therefore throughput canbe increased by eliminating the purge step.

Reference throughout this specification to “one embodiment,” “certainembodiments,” “one or more embodiments” or “an embodiment” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe disclosure. Thus, the appearances of the phrases such as “in one ormore embodiments,” “in certain embodiments,” “in one embodiment” or “inan embodiment” in various places throughout this specification are notnecessarily referring to the same embodiment of the disclosure.Furthermore, the particular features, structures, materials, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Although the disclosure herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent disclosure. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present disclosure without departing from the spiritand scope of the disclosure. Thus, it is intended that the presentdisclosure include modifications and variations that are within thescope of the appended claims and their equivalents.

What is claimed is:
 1. A processing method comprising: providing asubstrate surface having at least one feature thereon, the at least onefeature comprising a top, a bottom and a sidewall; forming a film on theat least one feature so that the film is formed on the top, bottom andsidewall; and treating the film with a plasma to change a property ofthe film on the top and bottom of the feature so that the top and bottomof the feature have a wet etch rate that is more than 10 times greaterthan the film on the sidewall, wherein treating the film comprisesexposing the film to a directional plasma having an ion concentrationgreater than or equal to about 10¹⁰/cm³.
 2. The method of claim 1,further comprising repeatedly forming the film and treating the filmsequentially to deposit a film of a total thickness.
 3. The method ofclaim 1, wherein the film comprises SiN.
 4. The method of claim 1,wherein the plasma comprises one or more of hydrogen, argon, nitrogen,ammonia, oxygen or helium.
 5. The method of claim 1, wherein thedirectional plasma is a remote plasma formed in a plasma assembly havinga slot with edges through which the plasma flows.
 6. The method of claim1, wherein forming the film comprises sequentially exposing thesubstrate surface to a silicon precursor and a nitrogen reactant to forma silicon nitride film.
 7. The method of claim 6, wherein the substratesurface is exposed to a nitrogen precursor between exposure to thesilicon precursor and the nitrogen reactant, the nitrogen precursorcomprising a species that does not react with silicon precursormolecules on the substrate surface.
 8. The method of claim 7, whereinforming the film comprises sequentially exposing the substrate surfaceto a silicon precursor comprising dichlorosilane, a nitrogen precursorcomprising ammonia and a nitrogen reactant comprising a N₂/Ar plasma ora H₂/Ar plasma.
 9. The method of claim 7, wherein the plasma comprisesammonia and helium.
 10. The method of claim 9, wherein the wet etch rateof the top and bottom of the feature is greater than or equal to about20 Å/min.
 11. The method of claim 1, wherein treating the film occursafter a film having a thickness in the range of about 1 Å to about 50 Åis deposited.
 12. The method of claim 1, further comprising etching thefilm with dilute HF to selectively remove the film from the top andbottom of the feature.
 13. A processing method comprising: positioning asubstrate surface in a processing chamber, the substrate surface havingat least one feature thereon, the at least one feature having a top,bottom and sidewalls; exposing the substrate surface to a depositionenvironment comprising at least one deposition cycle, the depositioncycle comprising sequential exposure to a silicon precursor and anitrogen containing reactant to form a silicon nitride film on the top,bottom and sidewalls of the at least one feature; and exposing thesilicon nitride film to a treatment environment to modify the siliconnitride film deposited on the top and bottom of the at least one featureso that the film on the top and bottom have a wet etch rate that is morethan 10 times greater than the film on the sidewalls, the treatmentenvironment comprising a plasma having an ion concentration greater thanor equal to about 10¹⁰/cm³.
 14. The method of claim 13, wherein thedeposition cycle further comprises exposing the substrate surface to anitrogen precursor between the silicon precursor and the nitrogenreactant.
 15. The method of claim 14, wherein the silicon precursorcomprises dichlorosilane, the nitrogen precursor comprises ammonia andthe nitrogen reactant comprises an N₂/Ar plasma or a H₂/Ar plasma. 16.The method of claim 15, wherein the treatment environment comprises anammonia/helium plasma.
 17. The method of claim 13, further comprisingselectively etching the silicon nitride film from the top and bottom ofthe at least one feature.
 18. A processing method comprising: placing asubstrate having a substrate surface with a feature into a processingchamber comprising a plurality of process regions, each process regionseparated from adjacent process regions by a gas curtain, the featurecomprising a top, a bottom and a sidewall; exposing at least a portionof the substrate surface to a first process condition in a first processregion of the processing chamber, the first process condition comprisinga silicon precursor; laterally moving the substrate surface through agas curtain to a second process region of the processing chamber;exposing the substrate surface to a second process condition in thesecond process region of the processing chamber, the second processcondition comprising a nitrogen precursor; laterally moving thesubstrate surface through a gas curtain to a third process region of theprocessing chamber; exposing the substrate surface to a third processcondition in the third process region of the processing chamber, thethird process condition comprising a nitrogen reactant to form a siliconnitride film on the top, bottom and sidewalls of the feature; repeatingexposure to the first process condition, the second process conditionand the third process condition to form a silicon nitride film with apredetermined thickness; and moving the substrate surface to a fourthprocess region of the processing chamber, the fourth process regioncomprising a treatment environment comprising a plasma having an ionconcentration greater than or equal to about 10¹⁰/cm³ that selectivelydecreases the wet etch rate of the silicon nitride film on the top andbottom of the feature.